class Person:
    def __init__(self):
        self.name = 'dkfsj'
        self._age = 1

    def set_age(self, new_age):
        if 0 < new_age <= 120:
            self._age = new_age

    def get_age(self):
        return self._age


person = Person("小明")
person.set_age(20)
print(f"年龄为{person.get_age()}岁")
